Various crimp terminals have been proposed (refer to PTL 1). One conventional example of the crimp terminals is shown in FIG. 4.
In FIG. 4, a crimp terminal 50 is made of an electrically-conductive material. The crimp terminal 50 includes a mating terminal connection portion 51 for connection to a mating terminal, and a wire crimping portion 52 to which a wire W is crimped.
The mating terminal connection portion 51 extends forwardly from a bottom portion 53 of the wire crimping portion 52. The wire crimping portion 52 includes the bottom portion 53, a pair of conductor press-fastening portions 54 projecting respectively from opposite side edges of the bottom portion 53, and a pair of sheath press-fastening portions 55 projecting respectively from the opposite side edges of the bottom portion 53. A conductor w1 of the wire W placed on the bottom portion 53 is crimped by deforming the pair of conductor press-fastening portions 54, and two portions of a sheath w2 of the wire W placed on the bottom portion 53 are crimped by deforming the pair of sheath press-fastening portions 55, whereby the wire W is crimped to the wire crimping portion 52.
Three serrations 56a, 56b and 56c which are grooves are formed in a face of the bottom portion 53 on which the conductor w1 of the wire W is to be placed, and are disposed at a region where the pair of conductor press-fastening portions 54 are formed. The serrations 56a, 56b and 56c are disposed at substantially equal intervals in an axial direction of the conductor w1, and extend in a direction perpendicular to the axial direction of the conductor w1.
It is thought that the serrations 56a, 56b and 56c have advantages such as: an effect of cleaning between the conductor w1 and the bottom portion 53; an enhanced electrical performance due to an increased area of contact between the conductor w1 and the bottom portion 53; and an enhanced wire holding force, that is crimping characteristic, due to biting of the serrations into the conductor w1 and so on.
The Applicant has found that by providing a construction, as shown in FIG. 5, for reducing a shearing force of opposite end-side serrations 56a and 56c against the conductor w1 and securing a strong wire holding force (see PTL 1). In the construction, a central serration 56b among the three serrations 56a, 56b and 56c has an inverted trapezoidal cross-sectional shape, and its inner and outer angles θ2 are the same. Each of the serrations 56a and 56c disposed respectively at the opposite end sides among the three serrations 56a, 56b and 56c has an inverted trapezoidal cross-sectional shape and is bilaterally asymmetrical that its outer angle θ1 is formed into an obtuse angle larger than its inner angle θ2.
In order to confirm whether or not the angles of the three serrations 56a, 56b and 56c have been set respectively to the above-mentioned desired angles, it is necessary to accurately measure the angles of the three serrations 56a, 56b and 56c formed in the bottom portion 53. In order to accurately measure the angles of each of the serrations 56a, 56b and 56c, it is necessary to cut the bottom portion 53 along a cutting line 60 parallel to a direction L perpendicular to the direction of extending of each serration 56a, 56b, 56c and then to measure the angles of each serration 56a, 56b, 56c utilizing its cut surface, as shown in FIG. 6.